Flame pulsation suppressor for inshot gas burners



R. H. HARA April 11, 1961 FLAME PULSATION SUPPRESSOR FOR INSHOT GAS BURNERS Filed March 25 1959 HHHIIMMM MHIM INVENTOR. Raymond H. Hora H13 Af/omey FLAME PULSATION SUPPRESSOR FOR INSHOT GAS BURNERS Filed Mar. 25, 1959, Ser. No. 801,789

Claims. (Cl. 158-116) This invention pertains to inshot type gas burners, and particularly to a flame pulsation suppressor for inshot type gas burners.

It is well known that the flame of an inshot type gas burner tends to pulsate when used in conjunction with some types of combustion shells. This flame pulsation results in excitation of the air and flue gases Within the combustion shell and results in a resonant effect that is oftentimes objectionable. This invention relates to a device for suppressing flame pulsations by blending primary air with the gas flame at the end of the burner tube. Accordingly, among my objects are the provision of a flame pulsation suppressor for inshot type gas burners; the further provision of a device for blending primary air with the gas flame at the end of the burner tube in an inshot type gas burner; and the still further provision of a device of the aforesaid type comprising a pair of radially spaced coaxial tubes having a pair of axially spaced apertured annuli therebetween.

The aforementioned and other objects are accomplished in the present invention by providing a dampening chamber for the primary air and gas mixture in the burner tube proximate the flame. Specifically, the pulsation supressing device can be attached to a conventional inshot type gas burner or embodied as an integral part thereof. The device comprises a pair of coaxially arranged tubes, the outer of which has a stepped diameter, the smaller diameter of which telescopically receives the end of the burner tube and is rigidly attached thereto. The inner tube has, a portion disposed within the end of the burner tube and radially spaced therefrom so as to form an annular space between the outer wall of the inner tube and the inner Wall of the burner tube.

The coaxial tubes are interconnected adjacent their outer ends by a pair of axially spaced rings, or annuli. The outermost annuli has a plurality of circumferentially spaced circular holes therein, and the inner annuli has a plurality of circumferentially spaced, elongate arcuate slots therein. The inner tube divides the primary air and gas mixture flowing through the burner tube into two streams of substantially equal volume, one of which flows directly through the inner tube and the other of which flows in the annular space between the inner tube and the outer tube. The second stream passes through the slots in the first ring and the holes in the second ring and blends with the mixture of the first stream contiguous to the flame.

Secondary air for supporting complete combustion is supplied through an air tube through which the burner assembly extends. By utilizing the device of the present invention flame pulsations normally present at the end of the burner tube are substantially entirely suppressed. This effect is believed to be due to both the blending of part of the primary air and gas mixture in contiguous relation with the flame and by the dampening chamber which is formed in the annular space between the two tubes. Furthermore, the use of an inner ring having slots has been determined to be critical, since if both rings have circular holes the flame pulsations will not be suppressed.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

Figure 1 is a fragmentary view, partly in section and partly in elevation, of a warm air furnace embodying the flame pulsation suppressor of the present invention.

Figure 2 is a fragmentary sectional view of a flame suppressor constructed according to the present invention attached to the end of a burner tube.

Figures 3 and 4 are sectional views, respectively, taken along lines 3--3 and 44 of Figure 2.

With particular reference to Figure 1, the. invention is depicted in conjunction with a conventional warm air, gas fired furnace comprising an upstanding furnace housing 10 within which a combustion shell 12 is disposed. A burner mounting plate 14 is attached to the furnace housing it and supports an inshot burner assembly generally indicated by the numeral 16. The burner controls are mounted on the plate 14 externally of the furnace housing 10 and enclosed by a hood 18.- The burner assembly 16 projects into the combustion shell 12.

In accordance with conventional practice, a gas supply pipe 20 having a single outlet port communicates with a venturi 22 of ,a burner tube 24. The inlet side of the venturi is provided with the usual adjustable air shutter, not shown, for controlling the amount of primary air which is drawn into the burner tube 24 by the gas being discharged into the throat of the venturi 22. A second ary air tube 26 is likewise attached to the burner mounting plate 14, encompasses a part of the burner tube 24, and extends into the combustion shell 12. A flame spreader 28 supported by a bar 30 is located in alignment with and spaced from the end of the burner tube 24. The function of the flame spreader 28 is to shape the flame to fit the combustion shell 12. The bar 30 may be attached to a plate 32 which is secured to the burner tube 24.

With particular reference to Figure 2, heretofore the flame projecting from the end of the burner tube was merely allowed to impinge against the flame spreader 28. Since gas is supplied to the venturi 22 through a single port which terminates proximate the throat of the venturi, this type of burner is known as an inshot burner. The primary air and gas mixture is supplied through the tube 24 and is ignited at the end of the tube 24. As alluded to hereinbefore, it is a characteristic of inshot gas burners to have a pulsating flame. Moreover, in some instances the flame pulsations are of sufficient magnitude to excite the air and flue gases within the combustion shell and thus produce a resonant effect which amplifies the sound of the flame pulsation thereby resulting in objectionable noise. 1

*In the present invention, a pulsation suppressing device is attached to the end of the burner tube 24. This device comprises coaxial inner and outer tubes 32 and 34 which are held in spaced relation by a pair of axially spaced rings 36 and 38. The rings 36 and 38 are attached to the tubes 32 and 34 by welds. The outer tube 34 is of stepped diameter including a larger diameter portion 40 and a smaller diameter portion 42. The smaller diameter portion 42 snugly receives the outer end of the burner tube 24 and is rigidly attached thereto, such as by Welding. The inner tube 32 has a diameter less than the diameter of the burner tube 24 and projects into the end thereof so as to form an annular space 44 therebetween. The cross-sectional area of the passage in tube 32 is sub stantially equal to the cross-sectional area of the annular space 44. The annular space 44 connects with an annular space 46 between the tubes 32 and 34, and this space constitutes a dampening chamber which functions to suppress pulsations in the primary air and gas mixture flowing through the burner tube 24 and thus prevent flame pulsation. The cross-sectional area of the dampening chamber '46 is at least twice the cross-sectional area of the passage in tube 32. The tube 32 divides primary air and gas mixture flowing through the burner tube 24 into two streams of substantially equal volume, one of which flows through the tube 32 and is ignitedat the other end thereof. The second stream flows through the annular space 44 into the dampening chamber 46.

The ring 38, as shown in Figure 3, has four circumferentially spaced, circumferentially elongate arcuate slots 48 therein. The slots 48 subtend an angle of substantially 60 and are spaced substantially 30 apart. The primary air and gas mixture in the chamber 46 passes through the slots 48 into a chamber 50 between the two plates 36 and 38. As seen in Figure 4, the ring 36 is formed with a plurality of circumferentially spaced circular openings 52 in axial alignment with the slots 48 in the ring 38. The openings 52 are circumferentially spaced 225 apart. The slots 48 and the circular holes 52 are located on circles having the same radius from the axis of the tube 32. The primary air and gas mixture flowing through the circular holes 52 blends with the gas flame projecting from the tube 32, and secondary air for effecting complete combustion is supplied through the air tube 26, as shown in Figure 1.

Tests have indicated that the coaxial tube and baflie rings 36 and 38 effectively prevent resonant pulsation of the flame within the combustion shell 12. Furthermore, tests have indicated that the inner rings 38 must be slotted and the outer ring 36 must contain the circular holes in order to efiectively suppress flame pulsations.

While the embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A flame pulsation suppressor for an inshot type gas burner including, a burner tube, a pair of radially spaced coaxial tubes, the outer of which is telescoped over the end of the burner tube and is attached thereto, the inner tube extending into the burner tube so as to form an annular space between the inner wall of the burner tube and the outer wall of the inner tube, and a pair of rings interconnecting said coaxial tubes adjacent their outer ends and defining an annular chamber therebetween that communicates with the annular space between the inner tube and the burner tube, said rings being axially spaced,

. the inner ring having a plurality of circumferentially spaced, circumferentially elongate arcuate slots therein and the outer ring having a row of circumferentially spaced circular openings therein.

2. A flame pulsation suppressor for attachment to an inshot type gas burner, including, a burner tube, a first tube adapted to extend into the end of said burner tube and being radially spaced therefrom, a second tube radially spaced from the first tube and coaxial therewith, the second tube telescopically receiving the end of the burner tube, and a pair of axially spaced rings disposed between said first and second tubes to form a dampening chamber communicating with the annular space between the first tube and said burner tube, the outer ring having a circular row of circumferentially spaced circular openings therein and the inner ring having a circular row of circumfcrentially spaced, circumferentially elongate arcuate slots therein, the diameter of the circular rows in said first and second rings being equal.

3. A flame pulsation suppressor for an inshot type gas burner including, a burner tube, a first tube coaxial with the burner tube and extending thereinto, the first tube being radially spaced from said burner tube, a second tube of stepped diameter coaxial with the first tube and including a smaller diameter portion telescopically receiving the and of the burner tube and a larger diameter portion disposed at the outer end thereof, and a pair of rings interconnecting said tubes adjacent the larger diameter portion of the outer tube and forming a dampening chamber communicating with the radial space between the inner tube and said burner tube, said rings being axially spaced apart, the outer ring having a row of circumferentially spaced circular openings therein and the inner ring having a row of circumferentially spaced, circumferentially elongate arcuate slots therein.

4. The flame pulsation suppressor set forth in claim 3 wherein the cross-sectional area of the annular space between the inner tube and the burner tube is substantially equal to the cross-sectional. area of the passage in the inner tube.

5. The flame pulsation suppressor set forth in claim 3 wherein the cross-sectional area of the dampening chamber is substantially greater than the cross-sectional area of the inner tube.

References Cited in the file of this patent UNITED STATES PATENTS 1,644,610 Reichhelm Oct. 4, 1927 1,700,841 Graul Feb. 5, 1929 2,068,567 Palmer Ian. 19, 1937 2,134,169 Wright Oct. 25, 1938 FOREIGN PATENTS 595,514 Germany Apr. 13, 1934 

